A comparison of block copolymer surfactant gels

The aqueous gel forming properties of three series of block copolymer surfactants, poloxamers, poloxamines, and Butronic® polyols, are briefly reviewed and compared. The differences in their gel formation properties are explained. Aqueous gel formation of these polymers is attributed to the aggregation of extended linear coil micelles in which the hydrophilic ends become entangled as the temperature rises, due to dehydration. The failure of the Butronic polyol gels to exhibit the same reverse thermal behavior shown by the other two polyol series is attributed to a more lipophilic hydrophobe and to the larger number of moles of water associated with the Butronic hydrophile. The reverse thermal characteristics of aqueous poloxamer and poloxamine solutions has led to the development of aerosol detergent systems which can form foamy gels, thereby expanding the usefulness of these surfactants.     

Obituary: Rodney R. Cocking (1943-2002).

R. R. Cocking was born on January 11, 1943, in Casper, Wyoming, to a family deeply rooted in the culture of the West. Shortly after his 59th birthday, Cocking was murdered. His death is a great loss to his family, his friends and colleagues, and the field. Cocking was interested in behavioral development, child development, cognitive development, and learning and educational environments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discrimination of contour-deleted images by pigeons.

Three experiments attempted to determine which properties of pictorial representations of objects control their discrimination by pigeons. A particular focus was whether the representation mediating such discriminations could be described by the simple viewpoint-invariant primitive volumes of I. Biederman's (1987) recognition-by-components theory of object recognition or by J. Cerella's (1990) particulate features. In all 3 experiments, pigeons were first trained to discriminate drawings of 4 stimulus objects with half of the contour deleted but with the component geons postulated by Biederman's theory recoverable. Discrimination accuracy was then compared for test items containing the original particulate features, affording the retrieval of the original component geons, or having neither of these properties of the training stimuli. Although response accuracy was significantly greater when the component geons of the original objects were retrievable, measurable control over recognition by the particulate features of the objects and by their specific locations was also found. The results are consistent with the idea of component geon recognition as one of the important factors in object discrimination. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

(Hu)man versus mean revisited: MMPI group data and psychiatric diagnosis.

Used a meta-analysis of Minnesota Multiphasic Personality Inventory (MMPI) data from 403 control and psychiatric samples to (1) examine demographics associated with previously published MMPI studies, (2) test L. R. Goldberg's (1972) indexes for predicting normal versus deviant and neurotic versus psychotic group membership, (3) compare multiple regression, discriminant function, and logistic regression analyses commonly used to study the relation between the MMPI and diagnostic group membership, and (4) examine the signal within the MMPI as it related to current psychiatric diagnosis. Group data were found to be efficient indicators of the relation between the MMPI and diagnosis, although efficiency is compromised by within-sample heterogeneity. The 3 statistical methods examined obtained equivalent results. Regression models related to group prediction are presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Altered state of hypnosis: Changes in the theoretical landscape.

Presentations of theories of hypnosis in scholarly and introductory texts portray the field as dominated by two warring camps, variously referred to as state and nonstate or as special process and social psychological. Current issues and theories in the hypnosis literature are examined. In the process, we seek to dispel the myth that hypnosis theorists can be grouped into two camps. Although there is considerable controversy about the nature of hypnosis, no issues separate all so-called special process theorists from all social psychological theorists. Instead, virtually all substantive differences between theorists cut across this apparent distinction. Furthermore, the positions taken on many of the important issues dividing the field can no longer be portrayed as simple dichotomies, such as state vs nonstate or trait vs situation. Positions on these issues can more accurately be described as points on a continuum. We conclude by drawing attention to specific questions and issues that remain unresolved. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

X-ray diffraction from intact tau aggregates in human brain tissue

We describe an instrument to record x-ray diffraction patterns from diseased regions of human brain tissue by combining an in-line visible light fluorescence microscope with an x-ray diffraction microprobe. We use thiazine red fluorescence to specifically label and detect the filamentous tau protein pathology associated with Pick's disease, as several labs have done previously. We demonstrate that thiazine red-enhanced regions within the tissue show periodic structure in x-ray diffraction that is not observed in healthy tissue. One observed periodicity (4.2 ?) is characteristic of cross-beta sheet structure, consistent with previous results from powder diffraction studies performed on purified, dried tau protein.     

Photothermal radiometric detection and imaging of surface cracks

This paper discusses surface crack detection by photothermal radiometric imaging (PRI). In PRI, also called dynamic infrared scanning, a surface is scanned with a spot of heat. Imperfections are detected by radiometrically sensing changes in the surface temperature of a small area in the vicinity of this spot. In the work described, cracks narrower than 25 µm (0.001 in.) in a lightly rusted steel surface have been detected. Indiscrete scanning an amplitude modulated heating beam is moved in steps, remaining at each location long enough to measure amplitude and phase of the AC temperature. Incontinuous scanning a constant intensity heating beam is moved continuously while the temperature deviations are measured. This paper presents methods of calculating amplitude and phase of surface temperature for discrete scanning and instantaneous temperature for continuous scanning across a surface crack. For a steel surface scanned by a watt-level laser beam, predicted surface temperature deviations when crossing the crack are several degrees Celsius, with expected radiometrically detected power several orders of magnitude above the detector noise. In experiments performed, both techniques easily detected narrow cracks in a smooth, clean surface. Discolorations and pits, on the other hand, generate a disturbing type of surface noise. This noise was minimized by differential detection. Based on results obtained, continuously scanned PRI with a fan-type heating beam and array detection could become a viable way of mapping surface cracks at practical scanning speeds.     

Recognition-by-components: A theory of human image understanding.

The perceptual recognition of objects is conceptualized to be a process in which the image of the input is segmented at regions of deep concavity into an arrangement of simple geometric components. The fundamental assumption of the proposed theory, recognition-by-components (RBC), is that a modest set of generalized-cone components, called geons, can be derived from contrasts of five readily detectable properties of edges in a two-dimensional image. The detection of these properties is generally invariant over viewing position and image quality and consequently allows robust object perception when the image is projected from a novel viewpoint or is degraded. RBC thus provides a principled account of the heretofore undecided relation between the classic principles of perceptual organization and pattern recognition. The results from experiments on the perception of briefly presented pictures by human observers provide empirical support for the theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thymocyte development in the absence of pre-T cell receptor extracellular immunoglobulin domains

Immature thymocytes express a pre-T cell receptor (pre-TCR) composed of the TCRbeta chain paired with pre-Talpha. Signals from this receptor are essential for passage of thymocytes through a key developmental checkpoint in the thymus. These signals were efficiently delivered in vivo by a truncated form of the murine pre-TCR that lacked all of its extracellular immunoglobulin domains. De novo expression of the truncated pre-TCR or an intact alphabetaTCR was sufficient to activate characteristic TCR signaling pathways in a T cell line. These findings support the view that recognition of an extracellular ligand is not required for pre-TCR function.     

Delineation of female performance on the Rey-Osterrieth Complex Figure.

103 female college students (aged 18–24 yrs) were administered the Rey-Osterrieth Complex Figure on Copy, Immediate Recall, and 20-min Delayed Recall. Ss were grouped based on handedness, familial handedness, and academic major (mathematics/science and nonmath/science). Based on the scoring system of D. Waber and J. Holmes (see PA, Vols 72:24305 and 74:9917) the mathematics/science anomalous dominance groups obtained higher mean scores than all other subgroups, and the non-math/science familial right-handers were the low performers. The high-performing groups may have an increased ability to coordinate the use of left- and right-hemisphere processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)